Compact collapsible microform viewer

ABSTRACT

A microform viewer has a case section pivotally mounting a screen, to move from a collapsed position to a viewing position, and slidably receiving a two-part projection section that telescopes into the case section. As the projection section moves into and out of the case section it positively drives the screen between collapsed and display positions. The projection section is made of two mutually separable housings that fit together along the film path so that when the two housings are separated the two pressure plates forming part of the film path are readily accessible.

BACKGROUND OF THE INVENTION

The present invention relates to microform viewers and more particularlyconcerns an improved image projector that facilitates maintenance offilm path, and which, in another aspect, readily lends itself to acompact collapsible packaging arrangement of the viewer.

In typical microform viewers selected ones of a number of images formedon a film or microform are projected for enlarged display on the viewerscreen. The film is positioned between a light source and projectionlens system that projects light to be reflected by one or more mirrorsto the viewing screen. To select an image, the film is moved indifferent directions through a film path which closely confines a chosenportion of the film between a pair of transparent glass flats. A majorproblem encountered in the use of such viewers is lack of cleanliness ofthe flats. The flats are exceedingly difficult to clean and maintain ina state of cleanliness because they are so close to each other. In mycopending application for Microform Viewer, Ser. No. 066,935 filed Aug.16, 1979, now U.S. Pat. No. 4,327,974, I have shown a pair of flats thatare removable as a unit and, being hingedly connected to each other, canbe readily moved apart for cleaning. Nevertheless, relatively complexmechanism and springs are required to removably mount these flats andcare must be exercised in the direct handling of the flats themselvesfor cleaning, removal and insertion.

Accordingly, it is an object of the present invention to provide aprojection system which further facilitates maintenance of filmpositioning structure.

Partly because of the small size of the images to be viewed in themicroform viewer, a relatively long optical path is employed to obtainrequired magnification. Even with optimum bending or folding of theoptical path, required viewer size is inherently incompatible withoptimum compactness desired for ready handling and portability. To thisend, collapsible viewers have been devised. Various types of folding andexpandable mirror and screen arrangements have been provided. Film andlens systems have been shifted to extend the optical path for viewing atproper magnification. Typical of such arrangements is the viewer shownin the patent to Edelstein, U.S. Pat. No. 3,899,246, in which a pair ofmirror sections, folded together to form sides of the viewer case, arepivoted outwardly to provide an elongated optical path. A folding mirrorarrangement is also shown in my co-pending patent application identifiedabove. In the Edelstein patent, the degree of magnification may bechanged by moving the entire film and lens section toward and away fromthe reflectors and, moreover, this section may be entirely detached forprojection on a fully displaced and more remote screen. Nevertheless, inthe manipulation of these devices, the several moving parts must beseparately moved between open and closed positions, requiring severaldifferent and independent operations. Yet proper location of all theparts in their desired positions and inadvertent detachment are notadequately assured.

Accordingly, it is another object of this invention to provide a compactcollapsible viewer in which a viewing screen is automatically andpositively driven between closed and display positions as a projectingsection is moved between a collapsed position telescoped within theviewer case and an extended position in which it is withdrawn from itstelescoping position. Another object is to provide viewer sections thatare readily separable intentionally but not inadvertently.

SUMMARY OF THE INVENTION

In carrying out principles of the present invention in accordance with apreferred embodiment thereof, an optical projector is formed of firstand second housings that define a film receiving path therebetween andthe two housings are mutually separable at the film receiving path. Thefilm receiving path is formed in part by pressure plates that closelyand movably confine a film therebetween and are mounted respectively tothe first and second housings so that separation of the housingsprovides access to the plates. According to another feature of theinvention, a microform viewer has a projection section telescopicallyassociated with a case section and slidably mounted thereto for motionbetween a closed position and an operative position. A screen section isshiftably connected to the case section for movement between retractedand display positions and means are provided for interconnecting theprojection and screen sections to drive the screen section betweenretracted and display positions in response to motion of the projectionsection between closed and operative positions. Solely in a particularintermediate position the projection section is completely separablefrom the case and screen sections, in one embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a pictorial illustration of a microform viewer embodyingprinciples of the present invention, illustrated in closed condition;

FIG. 2 is a view similar to FIG. 1 showing the viewer of FIG. 1 inoperative position;

FIG. 3 is a section taken on lines 3--3 of FIG. 2;

FIG. 4 is a section taken on lines 4--4 of FIG. 3;

FIG. 5 is an exploded pictorial view showing the four major parts of theviewer FIGS. 1-4;

FIG. 6 is a pictorial view of one of the projector section housings;

FIG. 7 illustrates a modified form of viewer in closed condition;

FIG. 8 shows the viewer of FIG. 7 in extended position;

FIG. 9 is a section, taken on lines 9--9 of FIG. 8;

FIGS. 10 and 11 are sections, taken on lines 10--10 and 11--11 of theviewer of FIG. 9;

FIG. 12 is a perspective view, with parts broken away, of the case andscreen sections of the viewer of FIGS. 7-11;

FIG. 13 is an exploded view, looking at the bottoms of the separablehousings of the projection section of the viewer of FIGS. 7-11; and

FIG. 14 is a simplified schematic view illustrating the manner in whichthe projection and case sections of the viewer of FIGS. 7-11 aredetachably interconnected.

DETAILED DESCRIPTION

Referring now to FIGS. 1-6, the microform viewer of the presentinvention is formed of three main sections, a case section 10, a screensection 12 and a two-part projection section 14. As can best seen inFIG. 5, the two-part projection section 14 includes a first housing 16and a second housing 18 separably connected to the first housing. Casesection 10 is a generally rectangular hollow housing open at both topand rear and includes a bottom wall 20, a forward wall 22 and sidewalls24,26. The sidewalls each have rear end portions 28,30 that are spacedmore closely together than are the sidewalls 24,26. The relatively closespacing of rear sidewall portions 28,30 provides for a snug fit aboutthe projection section and provides an enlarged portion of the casesection cooperating with the screen section 12. Longitudinally extendinginwardly projecting flanges 32,34 are fixed to the case sectionsidewalls adjacent to but spaced above the bottom 20 to providelongitudinally extending guide ways 36,38. Fixed mutually aligned pivotpins 42,44 extend laterally outwardly from upper rear corners ofsidewall portions 28,30 and arcuate slots 46,48 formed in these sidewallportions have curvatures centered upon the common axis of the pivot pins42,44. A mirror 50 is mounted within the case section, extending at anangle upwardly and forwardly from the bottom wall 20 to the upper edgeof the front wall 22 and exxtending from side to side between thesidewalls 24,26.

Screen section 12 is pivoted to the case section and is formed of agenerally rectangular upper frame member 56 having a front wall 58 andsidewalls 60,62. A viewing screen 64 is fixedly mounted within the frame56. The screen section has a front wall 66 formed with a laterallyelongated opening that straddles the case section rear wall portions28,30 in closed position. Fixed to and extending rearwardly from therear wall 66 are a pair of spaced ears 68,70 formed with coaxial pivotapertures of which only that indicated at 72 is shown (there being amating aperture on the inner surface of ear 68). These aperturespivotally receive pivot pins 42,44 to thereby mount the screen section12 for pivotal motion from its retracted position as shown in FIG. 1, toa display position shown in FIGS. 2 and 3. In retracted position, thescreen closely overlies the upper edges of the case section and theseveral walls of the screen section telescopically receive thecorresponding walls of the case section, whereas in display position,the screen section and the screen 64 are displaced from the casesection.

Ears 68,70 are formed with a pair of inwardly projecting mutuallyaligned cam pins of which only one, indicated at 74, is shown in FIG. 5.These two cam pins (there being a corresponding cam pin projectinginwardly from the ear 68) extend through and slightly beyond the arcuateapertures 46,48 formed in case section walls 28,30 and cooperate withcamming means (to be described below) on the projection section so thatthe screen is directly and positively driven between retracted anddisplay positions by motion of the projection section between closed andoperable positions.

The projection section 16 is mounted upon a flat generally rectangularbase 78 of which the edges form a pair of guides slidably received inthe guide ways 36,38 of the case section, to allow the projectionsection to telescope into and out of the case section. Base 78 forms thebottom of the first or lens housing which includes a lens compartmentformed by sidewalls 80,82, upper or top wall 84, and a rearwardly facingwall 86 in which is mounted a pressure plate in the form of atransparent optical glass flat 88. Rear wall 86 is apertured and carriesa fixed forwardly extending internally threaded sleeve 90 (FIG. 3) inwhich is threaded a lens 92 having an externally threaded rear endportion and a fixed focusing thumb wheel 94 of an enlarged diameter thatenables the thumb wheel 94 to project slightly above the top wall 84through a slot 96 formed therein.

Sidewalls 80,82 of the first housing are made of double thickness andoutwardly opening angulated cam slots 98,100 are formed therein toreceive the respective cam pins 74 inwardly projecting from the screensection ears 68,70 through the case section wall slots 46,48. Cam slots98,100 include an upper substantially horizontal portion 102 (FIG. 5), adownwardly and rearwardly inclined portion 104 and a short rearwardlyhorizontal portion 106.

Rear wall 86 and flat 88 of the first housing form a substantially flatrearwardly facing surface that defines one portion of a film receivingpath. A curved wall 108 extends rearwardly and downwardly from thelowermost portion of flat 88, providing a continuation of the surface ofthis flat, and thence curves upwardly to a rearmost end 110. Fixed tothe end 110 of curved wall 108 and to the bottom plate 78 are upstandingside wall sections 112,114 terminating in inwardly directed rear flanges116,118 that extend for a substantial vertical distance. These flangesform vertically extending guides that help to detachably receive theseparable second housing of the projection section.

The second or lamp housing of the projection section includes an upperwall 120, and sidewalls 122,124 of increased thickness in which areformed outwardly facing cam slot extensions 126,128 that are alignedwith and horizontally extend from the rear horizontal end portions 106of cam slots 98,100. The second housing includes an angulated rear wallhaving a vertical portion 130 and a horizontal portion 132 forming arecess in which is mounted the operator 134 of a controlling switch 136(FIG. 3). An external receptacle 137 is mounted in rear wall 130 andelectrically connected to provide power through the switch 136 to aprojector lamp to be described below. The receptacle is adapted toreceive a plug-in electrical cord (which may have a suitable voltagestep down transformer) that is to be connected to a power source. Alower rear wall 140 extends downwardly from wall section 132 of thesecond housing and has fixed forwardly extending flanges 142,144 (FIGS.4 and 5) which cooperate with vertically extending angulated guideflanges 146,148 to form guide ways that slidably receive the firsthousing guides 116,118. The second housing section has a curved bottomwall 158 which mates with and is slightly displaced from the wall108,110 of the first housing section, forming part of the film path.

The second housing section has a front wall 160 (FIG. 6) having anaperture in which is fixed a second pressure plate in the form of anoptical glass flat 162, and having relatively short rearwardly extendingflanges 163, 163a, 164, 164a which are a hand tight friction fit withinthe open forward end of the second housing section defined by its upperwall 120, curved bottom wall 158 and sidewalls 122. The front wall 160and flat 162 are detachable from the front of the lamp housing toprovide access to a lamp 164 mounted in a socket 166 upon an upstandinglamp support 168 fixed to the curved bottom wall 158. A reflector 170and shroud 172 direct light from lamp 162 through the apertured frontwall 160 and through the glass flat 162.

It will be seen that each of the two housings of the projection sectionhas a substantially flat surface adjoining a curved surface to define afilm receiving path when the two housings are mated and telescopicallyinterengaged as shown in FIG. 3. The film path is provided between theflats 88,162 which precisely position and closely confine the film inthe optical path. The film path extends rearwardly and downwardly in acurve from its planar portion between the flats, so that a section ofmicroform may be manually inserted between the upper rearwardly andforwardly facing bevelled edges (see FIG. 3) of the first and secondhousings, into the film path between the flats.

In use, the viewer is carried and handled in its compact collapsedcondition as illustrated in FIG. 1. It is opened simply by withdrawingthe projection section from the case section which automatically raisesthe screen to its display position. The line cord is plugged intoreceptacle 137, the switch is turned on, and a film strip is manuallyinserted into the film path. The film strip is manually manipulateduntil a selected image is displayed on the screen, the image beingfocused by operation of the focus wheel 94. The lens is readilyaccessible from the open front end of the first housing of theprojection section. The lamp 164 is readily accessible by simplyremoving the frictionally held front wall 160 and its glass flat 166from the lamp housing. The glass flats 88 and 162 are readily accessiblefor cleaning, maintenance, or replacement, if necessary, simply byremoving the lamp housing from its telescopic relation with the lenshousing, which immediately exposes both the flats and also enablescleaning and maintenance of the remainder of the film path. If deemednecessary or desirable the cam slot may be opened forwardly to enablethe projector section to be detached from the case and screen sections.

FIGS. 7-14 illustrate a presently preferred form of viewer having twolenses to provide selected magnification, a more readily adjustable filmpositioning arrangement and an improved interconnection of the case andprojection sections that allow the projection section to be completelywithdrawn for use as an independent projector, while significantlyminimizing the possibility of inadvertent detachment.

Three main viewer sections include a case section 210, a screen section212, and a two-part projection section 214 that includes a first or lenshousing 216 and a second or lamp housing 218 separably connected to thefirst housing. Case section 210 is a generally rectangular housing openat both top and rear, and includes a bottom wall 220, forward wall 222,and sidewalls 224, 226. The sidewalls each have rear portions 228, 230,that are spaced more closely together than are the forward sidewalls andprovide for a snug fit about the projection section. Bottom wall 220 ofthe case section is provided with longitudinally extending upwardly openguide channels 232, 234, (FIG. 12) depressed slightly below the bottomwall 220. The latter has laterally outwardly extending guide elements236, 238 extending partly across the guide channels 232, 234. Guideelements 236, 238 are of a limited longitudinal extent for purposes tobe described below.

Fixed coaxial pivot pins, of which that designated at 244 is shown inFIG. 12, extend laterally outwardly from upper rear corners of sidewallportions 228, 230 and arcuate slots 246, 248 formed in these sidewallportions have curvatures centered upon the common axis of the pivotpins. A reflector 250 is mounted at the forward portion of the casesection. Screen section 212 is pivoted to the case section and formed ofa generally rectangular frame with a viewing screen 264 fixed thereto.The screen section has a front wall 266 formed with an openingstraddling the case section rear wall in closed position, and a pair ofrearwardly extending, mutually spaced ears 268, 270 having aperturesthat pivotally receive the case section pivot pins to mount the screensection for its pivotal motion between the retracted position of FIG. 7and the display position of FIG. 8. Ears 268, 270 are formed with a pairof inwardly projecting mutually aligned cam pins of which one, indicatedat 274, is shown in FIG. 12.

The projection section is mounted upon a flat generally rectangular base278 carrying downwardly spaced and inwardly projecting guide elements278a, 278b, 278c, and 278d, all spaced below the base 278. The guides oneither side of the base plate 278 are each discontinuous, being formedon the one side of a forward guide element 278a and a rear guide element278b, which are longitudinally spaced from one another by a distance notless than, and preferably slightly greater than, the longitudinal extentof the laterally outwardly projecting guide element 236 on thecorresponding side of the case section bottom wall. Similarly, the guideon the other side of the projection base is formed of forward and rearguide elements 278c and 278d which are mutually spaced from one anotherby a distance not less than, and preferably slightly greater than, thelongitudinal extent of the guide element 238 of the case section. Thisarrangement provides for sliding telescopic guiding of the case andprojection sections and allows the two to be detached from one anotheronly at a single position of the projection section relative to the casesection, as will be more particularly described below.

Base 278 forms the bottom of a first or lens housing including a lenscompartment having sidewalls 280, 282 and upper or top wall 284 having adepressed rear portion 285 and a rearwardly facing wall 286 in which ismounted a film pressure plate in the form of a fixed transparent opticalglass flat 288.

Rear wall 286 is apertured as at 287 and supports a lens carrier that isslidably mounted in the lens housing for transverse motion. The lenscarrier includes a rear wall 271 having its lower edge slidably mountedin an upwardly facing lower guideway 273 carried on the wall 286 andfixedly mounting a pair of laterally spaced internally threaded lenssleeves 275, 277 (FIG. 11). Threaded in the lens sleeves forlongitudinal focusing adjustment are lenses 279, 281, each having afixed focusing wheel 283, 285 extending upwardly through a slot 287 in atop wall 289 of the lens carrier.

The rear depressed portion 285 of the top projector wall is formed witha focusing opening 291 that permits access to lens focusing wheels andalso has a transversely extending slot 293 through which projects anupwardly extending lens selector actuator 294 that is fixedly connectedto the carrier wall 271. Part of the upper edge of the latter extendsinto slot 293 to guide the carrier.

The guide 273 which slidably retains and guides the lower edge of lenscarrier wall 271 is formed with an inverted V-shaped aperture whichreceives the inverted V-shaped bent end 295 of a resilient carrier latchor spring 296 that is secured to the bottom of the guide 273. Thelowermost edge of the carrier wall 271 is formed with a pair of spaceddownwardly opening notches 297a and 297b which alternatively receive thebent spring latch 296 to hold the carrier and lenses in one of their twolaterally slidable selected positions.

Sidewalls 280, 282 of the lens housing 216 of the projection section aremade of increased thickness and outwardly opening inclined slots 298,300 are formed therein to receive the respective cam pins 274 inwardlyprojecting from the screen section ears through the case section wallslots. The cam slots 298, 300 include a short forward substantiallyhorizontal portion 302, a downwardly and rearwardly inclined portion 304and a notched portion 306 formed in the lower edge of each slot justahead of the forwardmost portion of the inclined slot section 304.Horizontal slot portion 302 opens and slightly diverges forwardly toenable complete separation of the projection and casing sections, aswill be described below.

Pressure plate 288 of the lens housing forms a substantially flat,rearwardly facing surface that defines one portion of a film receivingpath. A curved wall 308 extends rearwardly and downwardly from thelowermost portion of the flat 288 providing a rearward horizontalcontinuation of this flat, and thence curves upwardly to a rearmost end310. Fixed to the curved wall end 310 and to the bottom plate 278, areupstanding rear wall sections 312, 314 (FIG. 11) terminating in inwardlydirected rear flanges 316, 318. These parts extend a substantialvertical distance and form vertical guides that help to attachablyreceive the separable lamp housing of the projection section. The lamphousing includes a pivotally mounted upper wall 320, sidewalls 322, 324including outwardly projecting overhanging portions 322a, 324a each ofwhich terminates in a vertically extending downwardly projecting rearwall portion 322b and 324b.

The lamp housing includes an angulated rear wall having a recess at itsupper end in which is mounted an operator 334 (FIG. 8) of a controlswitch 336 (FIG. 9). As in the previous embodiment, a receptacle 337 ismounted adjacent the switch operator 334 to enable electric power to besupplied through the switch to the lamp. A lower rear wall 340 extendsdownwardly and includes a pair of laterally positioned outwardlyextending guide elements 342, 344 spaced forwardly of wall 340 andforming outwardly opening guideways that slidably receive flanges 316,318 of the lens housing. The lamp housing section has a curved bottomwall 358 having a lower horizontal portion 360 terminating in ahorizontally extending forward section 358a.

The front wall of the lamp housing is formed by a movable pressure plate362 apertured as at 363 and pivotally connected at its lower edge 364 tothe lower front edge of the forward bottom wall portion 358a of the lamphousing. This pivotal connection is conveniently formed by extendingparts of the lower edge 364 rearwardly and loosely through horizontalslots formed in inwardly projecting support walls 366, 367 in which theextensions are captured by pins 368, 369 (FIG. 11).

First and second laterally spaced upstanding supports 370, 371 are fixedto the support walls 366, 367 within the second housing and slidablyreceive first and second mutually spaced removable heat sinks in theform of transparent glass plates 372, 373. Top wall 320 of the lamphousing is pivoted to the rear upper portions of the sidewalls to enableaccess to the interior of the lamp housing for the removal of the glassplates 372, 373 and for access to a removable lamp 374 carried in afixed lamp mounting 375. A spare lamp assembly 376 may be mounted withinthe lamp housing.

A pair of laterally spaced springs 380, 382 have rearward ends mountedon and bearing against inwardly projecting support walls 366, 367 thatare fixed to the sidewalls 322, 324. The forward ends of the springsbear against pressure plate 362 above its lower pivoted edge, and thusresiliently urge this pressure plate against the pressure plate, orglass flat 288, of the lens housing. The pressure plates and the wallsof the first and second housings of the projection section mutuallycooperate to define a film receiving path therebetween.

The viewer of FIGS. 7-14 is carried and generally handled in its compactfolded condition, as illustrated in FIG. 7. It is readied for operationin the same manner as is the viewer of the previous embodiment. Theprojection section is grasped and withdrawn from its telescopingrelation with the case section. Initially, in compact telescopedcondition, the driven cam pins 274 lie beneath, but closely adjacent,the overhanging laterally extending wall portions 322a and 324a of thesecond housing, and thus the screen section 212 is restrained frompivoting from its closed position.

As the projection section is withdrawn, cam pins 274 enter the rear endof the inclined cam slots 298, 300 and the lower surfaces of these camslots drive the cam pins and screen section upwardly as the projectionsection is further withdrawn. When the screen section 212 reaches itslimiting display position, the cam pins 274 engage the upper ends ofarcuate slots 246, 248 and further pivoting of the screen section isprevented. In the fully open position, with the screen in its displayposition and the projection section withdrawn to its operative position,as illustrated in FIGS. 8 and 9, further withdrawal of the projectionsection is prevented by the recess 306 and the lower portion 390 of theforward end of the cam slots (See FIG. 9). Lower portion 390 is abovethe bottom of the drive or cam pins 274 and thus the pins would have torise beyond the position of FIG. 9 in order to continue furtherwithdrawing motion of the projection or projector section. However,further upward motion of the pins 274 (and further pivotal motion of thescreen section) is prevented by their abutment with the upper end of thearcuate slots 246, 248. Recess 306 also acts to restrain inadvertentreturn of the projection section to closed position.

To separate the projection section from the casing section theprojection section must be moved to an intermediate position, betweenthe fully open operative position of FIG. 9 and the closed position ofFIG. 7. In such position, as illustrated schematically in FIG. 14, theoutwardly projecting guide elements 236 and 238 of the casing sectionare positioned in registration with the discontinuities or openingsbetween forward and rear portions 278a, 278b, 278c and 278d of theprojection section guide elements. Accordingly, in this position therear portion of the projection section may be tilted upwardly, raisingguide elements 278 past casing section guide elements 236, 238 until therear edge of the forward guide elements 278a and 278c just clear theupper surface of elements 236, 238 to the position illustrated in FIG.14. Now the projection section may be completely withdrawn. In thispartially tilted position of the projection section, the screen sectionmay be tilted upward slightly, but the forward portion 390 of the camslot and the recess 306 itself have been tilted downwardly so that therestraint of these elements on withdrawal of the projection section nolonger exists in this tilted position.

It will be seen that the probability of inadvertent detachment orseparation of the projection section is minimized since the projectionsection must first be moved to a precise intermediate position and thentilted before it is detached, whereas no tilting motion is necessary inthe normal operation of moving the projection section between its closedand operative positions.

Once the projection section has been removed as described in connectionwith FIG. 14, the lamp housing may be readily separated from the lenshousing by sliding the two apart along the several guide elements 316,318, 342, 344. When the two housings are separated, they separate alongthe film receiving path the surfaces of which are then readilyaccessible for maintenance. The self-contained lamp housing, whenseparated from the lens housing of the projection section, is operableas a self-contained portable light source. Provision of an aperturedpressure plate 362 that is resiliently driven toward the other pressureplate enables the projector to readily accommodate microforms ofdifferent configurations and different thicknesses, including filmelements both with and without frames or mounting structures.

Data stored on microforms is often in one of two different sizes, andthus different microforms may require different amounts ofmagnification. Accordingly, the viewer described and illustrated inFIGS. 7-14 is provided with two alternatively selectable lenses each ofwhich can be individually focused. The lenses are mounted on the commonlens carrier, which, in turn, can be slidably shifted laterally so as toposition either one or the other of the lenses in the light path. Bothlenses are readily shifted from one position to the other by laterallypushing the upwardly protruding actuator 294. Spring latch 295, 296helps to position each lens properly and also to hold it in its properposition. Since the uppermost edge of the focusing wheel of each lens isbelow the lower surface of the housing top wall 285 this wall does notinterfere with the slidable motion of the lenses and yet the focusingaperture need be large enough to accommodate access to only a singlelens.

There have been described simple, small package collapsible microformviewers expandable to operable positions with minimum effort, andincluding a projector formed of two separable housings that greatlyfacilitate maintenance and repair.

The foregoing detailed description is to be clearly understood as givenby way of illustration and example only, the spirit and scope of thisinvention being limited solely by the appended claims.

What is claimed is:
 1. A microform viewer comprisinga case section, aprojection section telescopically associated with said case section andslidably mounted thereto for motion between a closed position in whichat least a portion of the projection section is telescoped within saidcase section and an operative position in which at least part of theprojection section is displaced from the case section, said projectionsection including means for positioning film bearing an image to beprojected, means for illuminating such film, and means for projecting animage of said illuminated film, a screen section pivotally connected tosaid case section for movement between a retracted position adjacentsaid case section and a display position displaced therefrom, saidscreen section including a display screen, means in said case sectionfor reflecting light from said projection section to said screen, anddrive means for interconnecting said projection and screen sections todrive said screen section between its retracted and display positions inresponse to motion of said projection section between its closed andoperative positions, said drive means comprising a cam surface on one ofsaid projection and screen sections and a cam fixed to the other of saidprojection and screen sections in slidable engagement with said camsurface.
 2. The viewer of claim 1 wherein said cam surface comprises aforwardly open cam slot on said projection section and wherein said camcomprises a cam pin on said screen section slidably received in said camslot, said pin being detachable from said open cam slot to allow saidprojection section to be detached from said case section.
 3. The viewerof claim 2 wherein said forwardly open cam slot includes a recessadjacent a forward end thereof tending to resist inadvertentdisplacement of said projection section from said operative position. 4.The viewer of claim 1 wherein said projection section includes first andsecond housings defining a film receiving path therebetween, saidhousings being mutually separable at said film receiving path.
 5. Theviewer of claim 4 including means for positioning film in said path,said means for positioning including a transparent flat forming a partof said film receiving path and mounted to one of said first and secondhousings, whereby separation of said housings exposes said flat forcleaning or replacement.
 6. The viewer of claim 5 including a pressureplate mounted to the other of said housings, and resilient means forurging said plate toward said flat.
 7. The viewer of claim 4 including apressure plate movably connected at one edge thereof to one of saidhousings and forming part of said film receiving path, and means forurging said plate toward the other of said housings.
 8. The viewer ofclaim 1 wherein said drive means are mutually detachable, and whereinsaid projection section is movable to an intermediate position betweensaid closed and operative positions, and is detachable from said screensection when in said intermediate position, and means for preventingdetachment of said projection section when in said closed or operativepositions.
 9. The viewer of claim 8 wherein said projection section ismounted to said case section by interengaging guide elements, said guideelements having release sections free of interengagement when saidprojection section is in said intermediate position.
 10. The viewer ofclaim 1 wherein said projection section is slidably mounted to said casesection by interengaging guide means, said guide means comprisinginwardly projecting first guide elements on one of said case andprojection sections, each said element having forward and rear portionslongitudinally spaced from one another, and outwardly projecting secondguide elements on the other of said case and projection sections, eachsaid second guide element having a length not greater than thelongitudinal space between forward and rear portions of an associatedfirst guide element, whereby said case and projection sections can beseparated from one another by passing said second guide elements throughsaid longitudinal spaces.
 11. A microform projector comprising a firsthousing having a lens for projecting an image of illuminated film,asecond housing mounted to said first housing and having means forilluminating film bearing an image to be projected, said first andsecond housings defining a film receiving path therebetween, wherebyfilm may be moved and positioned in said path for illumination by lightfrom said first housing, and whereby an image of such illuminated filmmay be projected by the lens of the second housing, said projectorincluding a case section, said first and second housings being slidablymounted to said case section for motion between a closed position inwhich at least a portion of one of said housings is telescoped withinsaid case section and an operating position in which at least one ofsaid housings is displaced from said case section, a screen sectionmounted to said case section for movement between a retracted positionadjacent said case section and a display position displaced therefrom,said screen section including a display screen, and actuating meansinterconnecting at least one of said housings and said screen sectionfor driving the screen section between its retracted and displaypositions in response to motion of said one housing between its closedand operative positions.
 12. The projector of claim 11 wherein saidscreen section is pivotally connected to said case section and whereinsaid actuating means comprises detachably interengaged cam pin and slotmeans on said screen section and one of said housings, said first andsecond housings and said case section having detachably interengagedguide elements forming at least part of the slidable mounting of saidhousings to said case section.
 13. The projector of claim 11 whereinsaid housings are mutually separable at said film receiving path.
 14. Acompact collapsible microform viewer comprisingan open case sectionhaving a bottom, a forward wall, a pair of mutually spaced sidewalls andfirst and second laterally projecting pivot elements fixed to rearportions of said sidewalls, first and second arcuate slots formed insaid sidewalls, said section having first and second mutually spacedguide elements extending forwardly from the rear of said case section, areflector mounted in said case section adjacent said forward wall, ascreen section having a display screen mounted thereon and having a pairof mutually spaced rearwardly extending mounting brackets, each brackethaving a pivotal connection to one of said case section pivot elements,said screen section also including cam means fixed thereto, a projectionsection comprising a housing telescopically associated with said casesection and having longitudinally extending guide elements engaged withsaid case section guide elements to slidably mount the projectionsection to the case section for motion between a closed position inwhich at least a portion of the projection section is telescoped withinsaid case section and an operative position in which the projectionsection is at least partly displaced from the case section,and cam meanson said projection section engaged with the cam means of said screensection for pivoting said screen section relative to said case sectionin response to motion of the projection section between its closed andoperative positions.
 15. The viewer of claim 14 wherein at least some ofsaid guide elements are discontinuous to permit separation of saidprojection and case sections at an intermediate position between saidclosed and operative positions.
 16. The viewer of claim 14 wherein eachguide element of one of said projection and case sections isdiscontinuous and has a forward and rear portion longitudinally spacedfrom one another by a distance not less than the length of the guideelements of the other of said projection and case sections.
 17. Theviewer of claim 16 wherein said screen section cam means comprise a pairof inwardly extendng cam pins fixed to said screen section and extendingthrough said first and second slots of said case section, and whereinsaid projection section cam means comprises first and second outwardlyfacing open ended cam slots formed in said projection section andreceiving said screen section cam pins, whereby said cam pins may slideinto and out of said slot through the open ends thereof.
 18. The viewerof claim 14 wherein said projection section includes first and secondhousings defining a film receiving path therebetween, said housingsbeing mutually separable at said film receiving path.
 19. The viewer ofclaim 14 wherein said projection section includes a base, a firsthousing mounted on said base, a second housing mounted on said firsthousing and defining therewith a film receiving path, said first andsecond housings being separable from one another along said path. 20.The viewer of claim 19 wherein said first housing includes asubstantially flat rearwardly facing surface and a second curved surfaceextending rearwardly therefrom, and wherein said second housing includesa substantially flat forwardly facing surface and a second curvedsurface extending rearwardly therefrom, said housings including slidablyinterconnected guide means for slidably and detachably mounting saidsecond housing to said first housing for motion between a connectedposition in which the surfaces of said first housing are positionedclosely adjacent and substantially parallel to corresponding surfaces ofsaid second housing to define therewith a film receiving path, and asecond position in which said first and second housings are detachedfrom one another to facilitate access to said surfaces.